Sprouts, microgreens, shoots or crests (herein referred to as sprouts) are a food produced by exposing seeds to conditions which cause them to germinate and grow into tiny plants. This has previously been done by exposing seeds to moisture by various methods such as immersion or spray. Seeds which are germinated into edible small plant forms include, but are not limited to, those from alfalfa, clover, mung bean, radish, mustard, broccoli, flax, green peas, sunflower, corn, wheat, soybeans, and others.
Seeds that are used for sprouting purposes are obtained from sources such as farm fields, and stored in places such as agricultural warehouses that may be contaminated with bacteria, fungi, or other organisms that can be harmful to health. For example, farm fields may become impacted with wildlife that carry microbial pathogens such as E. coli O157:H7, and salmonella, which can get spread to crops and ultimately to the seeds. Seeds harvested from such fields, and sprouts germinated from such seeds, may be contaminated (e.g., contaminated by such microbial pathogens).
Other organisms (e.g., spoilage organisms) with which sprouting seeds may be contaminated may interfere with the quality of sprouts by, for example, imparting to them a bad flavor or color, or by reducing shelf life.
Organisms harmful to the healthfulness and quality of sprouts may also come to be present with the seeds from sources other than seed harvest and transport. For example, water for soaking and spraying seeds and sprouts during washing and germination may be contaminated, as may be the processing machinery surfaces and even process air used for aeration of sprouting chambers. Furthermore, workers working in a sprout manufacturing plant can carry pathogens and transfer them to products directly through handling of the products, and/or indirectly by contaminating the production environment.
In the prior art, sprouts and microgreens are grown by methods which include soaking, sanitizing the seeds, placing the seeds in trays, drums or bags to allow for the growth to marketable size. Alternatively, seeds may be placed in retail containers, with irrigation holes in the bottom, over a foam or an absorbent material such as cellulose and sprouted in the same container in which they may ultimately be delivered to consumers, placing the containers on trays and irrigating the growing sprouts from overhead or from the bottom tray with the seeds being irrigated periodically via holes in the container. At the end of the growth cycle, the prior art containers are capped with a lid, labeled and sent to the market with open irrigation holes, which compromises the sanitary condition of the product and its package. Both of the foregoing prior art methods typically involve irrigation of the sprouts during all stages of their growth. For example, in one rotary drum method, sanitized seeds are grown for 4-6 days with constant rotation and irrigation of the drums, followed by washing of the sprouts and manual or automated packaging. At the end of the growth cycle, sprouts leaving the drums typically contain about 10,000,000 to 100,000,000 cfu (colony forming units) of bacteria per gram. A subsequent wash and sanitation may reduce this load of bacteria by only a factor of 10 or 100, but this reduction is rapidly undone by continued/more bacterial growth during subsequent storage.
With respect to prior art methods wherein the sprouts are grown in trays or containers (e.g., in the ultimate retail container), the trays and containers are typically placed on racks and are typically irrigated for the length of the growth cycle by means of overhead irrigation, or by means of entry points in the bottom of the trays or containers, through which the irrigation water may enter. The sprouts and microgreens, therefore, are exposed to contaminants that may enter with the irrigation water or with air that enters via the same pathway as the irrigation water, or via drainage holes that are provided for the irrigation water. Such holes for the entry and exit of irrigation water allow microbial contamination to be introduced throughout the growth cycle.
There is a pronounced need in the art for methods/means for protecting the healthfulness and quality of sprouts from pathogenic and spoilage organisms, by containing the growth for most of the growth cycle in a sanitary, closed, retail-ready container.